President Barack Obama's campaign and Democrats have raised $ 181 million combined in September, pulling in the most money in one month during his re-election bid.

Obama's fundraising haul topped the more than $ 114 million raised by his campaign and Democrats during the month of August. Republican presidential nominee Mitt Romney's campaign and Republicans have not yet reported September fundraising totals.

Obama says in a message on Twitter, the online social network, that more than 1.8 million people donated in September, including more than a half-million who had not donated before in 2008 or 2012.

Obama's campaign ended August with nearly $ 89 million in the bank. It did not release its current cash on hand.